V2 Vocabulary Building Dictionary

efficacy

noun

Definition:
effectiveness and ability to yield a planned and desired result

Synonyms:
effectiveness, efficiency, efficaciousness

Antonyms:
inefficacy, ineffectiveness

Tips:
Efficacy is sometimes alternated with efficaciousness. Efficacy is often used when referring to a drug or treatment's medical effectiveness. If something is described as efficacious, it works. Efficacy is often just a simpler, more sophisticated way of saying effectiveness. The related adjective efficacious means "effective."

Usage Examples:

The FDA is concerned with both safety and efficacy when it comes to approving new pharmaceuticals. (effectiveness)

The new drug is considered both safe and efficacious by the FDA. (effective) adjective

The efficacy of your innovative learning system is clear from the test results. (effectiveness)

The efficacy of the new cancer treatment has not been proven. (effectiveness)

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